Settling in Harlem, Randolph found work as switchboard operator in an apartment building, enrolled in the College of the City of New York (where he discovered Karl Marx), and helped organize the Independent Political Council, a debate group. A member of the Socialist party by 1916, and a popular street-corner orator, Randolph got a job doing political work for the Brotherhood of Labor, an employment office for African American migrants from the South and West Indian immigrants.
In 1917 his career as an organizer and activist took off when he and Chandler Owen, a longtime associate, launchedThe Messenger
a monthly magazine
that delved into politics, trade union news, and literary criticism, among other subjects. As editor, Randolph campaigned against lynching, U.S. participation in the First World War, and the segregation he witnessed in the trade union movement. In fact in 1919 he denounced the AFL as "the most wicked machine for the propagation of race prejudice in the country."
Because he believed black Americans would never gain political freedom without economic power, in 1918 Randolph helped organize the National Association for the Promotion of Labor Unionism Among Negroes
. He also supported the National Brotherhood of the Workers
an independent union organized in 1919 that combined black nationalism with trade unionism.
Impressed by Randolph's abilities, a group of Pullman porters invited him in 1925 to help organize their fledgling union, The Brotherhood of Sleeping Car Porters
. Although it would take ten years for the Brotherhood to gain an AFL charter -- the first awarded to a union of black workers -- in 1937 the Brotherhood of Sleeping Car Porters would become the first black union to win a collective bargaining agreements.